How healthy is your local stream, lake or pond? Finding the answer requires looking at the three major components of water quality: chemical, physical and biological. Chemical is the one that most people think of when you talk about water quality – how much of a particular pollutant is in the water? But the biology, the critters that live there like fish, insects and mussels, and the physical habitat, like riffles and pools in streams or differing depths in a…